C. Julius Caesar, Gallic War

While these things are being done by Caesar, Labienus, leaving at Agendicum the recruits who had lately arrived from Italy, to guard the baggage, marches with four legions to Lutetia (which is a town of the Parisii , situated on an island on the river Seine ), whose arrival being discovered by the enemy, numerous forces arrived from the neighboring states. The supreme command is intrusted to Camalugenus one of the Aulerci, who, although almost worn out with age, was called to that honor on account of his extraordinary knowledge of military tactics. He, when he observed that there was a large marsh which communicated with the Seine , and rendered all that country impassable, encamped there, and determined to prevent our troops from passing it.